CARLSBAD – Greg Nelson balanced a basketball on one finger and that's all it took for the crowd to gather. Nine-year-old Andrea Lopez wanted to see if she could keep the ball spinning. Lucas Bradford, 10, wanted to show off his skills because he's double-jointed.

"Kids haven't changed," said Nelson, 55. "The world has changed around them but they are the same. They want to feel a part of something, to be encouraged. It's so easy to engage them."

The biggest surprise Nelson had for children at the Boys & Girls Clubs of Carlsbad yesterday was not a twirling ball, though.

He and his wife, Barbi, announced they have donated $1 million toward a $5 million fund-raising campaign to build a new club and headquarters east of McClellan-Palomar Airport.

The gift is the largest donation in the club's history, said its director, Ron Sipiora.

The Nelsons made the donation in January with no ceremony and asked to remain anonymous. Later, club directors persuaded the couple to talk about how the club changed Greg Nelson's life.

A 45-year love affair with the club prompted the donation, he said.

Nelson was 10 in 1959 when his mother first dropped off him and his younger brother, Doug, at the Carlsbad club downtown. Their father had left the family and Marcy Nelson needed somewhere for the boys to stay while she worked two jobs to make ends meet.

Nelson spent long days there. He learned leadership skills while organizing tennis tournaments, got to know Southern California by visiting such places as Disneyland, learned teamwork from basketball tournaments and made lifelong friends.

He later served as the club's athletic director and executive director before co-founding Don Joy Orthopedics out of his garage in 1980. He sold the company that now trades on the New York Stock Exchange and in 1989 co-founded another orthopedic equipment company, Breg. He sold Breg last year and now is a private investor.

The Nelsons have contributed money and organized fund-raisers for the club for years. They are co-chairs of the fund-raising campaign committee for the new club, and Greg Nelson is a lifetime member of the club's board of directors.

"Greg's generosity and ongoing commitment to helping the club that meant so much to him as a youth should be an inspiration to us all," said Carlsbad Mayor Bud Lewis, who named him Citizen of the Year in 1991. "It's an honor to work with him toward building a new Boys & Girls Club facility, which is desperately needed."

The downtown Carlsbad club has operated for more than 50 years. A branch at La Costa in a mobile unit was meant to be temporary but has been there for more than 22 years. Both clubs have waiting lists.

In December, Lennar Communities donated 1.17 acres of land worth an estimated $1 million for the new club. Lennar is the developer of Bressi Ranch, a 623-home development under construction at the southeast corner of Palomar Airport Road and El Camino Real. The club will be in Bressi Ranch.

The new club will be an 18,000-square-foot building with offices, a gym, game room, teen center, arts center, computer room, homework area and rooms for music, dance and aerobics.

About 250 children will be served at the new center.

The fund-raising campaign began in December and has raised nearly half the $5 million the club needs, Nelson said.

Construction is expected to begin in spring 2006. Club directors hope the club will be ready later that year.